By way of illustration, but by no means limiting in itself, the present invention will be explained in the motor vehicle field and more specifically in area of access control to a motor vehicle of the “hands free” type.
Currently, the generic operating principle of hands-free type access to a vehicle is as follows:                The vehicle is equipped with means (a computer totally or partly dedicated to this function) for identifying the approach of authorized people (generally wearing an electronic badge capable of dialoging securely with the identification means). A regular and frequent scan is carried out in order to determine whether the badge of an authorized person is in the immediate vicinity of the vehicle.        When an authorized person approaches, the identification means nevertheless wait for said person to actually show the intent to enter before unlocking the opening or openings of the vehicle. The aim of this two-fold check is to allow—for example—an authorized person to pass close to his vehicle without in any way specifically unlocking access thereto or else unlock just one opening.        
In this device, one of the means that can be used to determine the actual intent of the authorized person to enter into the vehicle consists in placing in the handle of the openings a proximity sensor that will enable the identification means to be informed (when the authorized person extends the hand toward the handle of the opening). Such a sensor type is, for example, of capacitive type and then sends a proximity detection signal to the identification means. If the two-fold condition stated previously is fulfilled (detection of the authorization in the form of a badge and detection of a part of the body—generally a hand—close to the handle of the opening), then unlocking takes place and access is authorized.
In this particular scenario, the capacitive sensor is incorporated in the handle of the opening.
A recent trend has been to replace, in the opening handles, the mechanical locking and unlocking control with an electronic device. It follows that, on a door handle—for example—two areas are available to the user; the first area is used to open the door by means of a capacitive sensor which detects the proximity of the hand (as described previously) and the second area, also equipped with a capacitive sensor, is used to detect the will of the user to lock or unlock the access to the vehicle.
The use of two capacitive sensors does, however, present a problem of possible interference. Those skilled in the art have partially resolved this drawback by distancing the two sensors from each other within the handle. This makes it possible to have two clearly distinct areas with different effects for the user and to restrict the risks of interference.
Since the dimensions of a vehicle handle are nevertheless inherently restricted, the two sensors are forced to share a common space. This has the effect of creating a real disturbance in case of rain or high atmospheric humidity. In practice, the moisture that infiltrates into the handle creates couplings between the different sensors and erroneous detections then occur.
Those skilled in the art have proposed making the handle watertight by various methods. One of the methods used consists in coating the capacitive sensors in a resin made of plastic material (of polyurethane or of epoxy resins for example). This method is unfortunately long and costly. Furthermore, it is difficult to easily mold sensors of complex forms. One proposed alternative is to facilitate the flow of the water present in order to avoid its presence. This technical solution is not satisfactory because it would entail the presence of flow orifices that are incompatible with the aesthetic demands and facilitates the coupling between the capacitive sensors in very damp atmospheres (rain, mist, etc.) because of the very flow orifices that render said handle non-watertight.